Oxygen mask



Patented Mar'. 21, 1944 UNITED STATES PATENT OFFICE This invention relates to devices for administering oxygen to aviators, and more particularly to the equipment carried on the person of an aviator for this purpose, as distinguished from oxygen reservoirs, valves, etc., for supplying oxygen from a high pressure source at a desired low pressure.

Probably the simplest method of supplying oxygen to aviators is to provide a tube carrying oxygen from a suitable source at low pressure, the end of which tube the aviator inserts in his -mouth and holds between his teeth. This method has the serious disadvantage of requiring constant attention on the part of the aviator in order to maintain the tube in position. Furthermore, it does not provide for the rebreathing of any exhaled air which I find is desirable to promote deep breathing. It is also objectionable in that oxygen is supplied continuously, and is wasted during exhalation ifthe aviator exhales through his mouth.

Some of the foregoing defects of a simple oxygen tube were i-mmediately recognized, and attempts made to avoid them by providing a breathing connection utilizing some sort of mask fitting over the nose and mouth, and by providing an external reservoir, such as a rubber bladder, for storing oxygen during exhalation and making it available during the next inhalation. However, all of the prior masks of which I am aware have been subject to the criticism that they were awkward to use, reduced the eiliciency of the aviator, and had loose parts connected thereto which might be subject to damage, besides being in the Way ofthe aviator and interfering with his speech.

A broad object of the present invention is to provide an oxygen mask for aviators that is highly eflicient from the standpoint of supplying oxygen in proper amounts without wastage, and at the same time is comfortable to wear, is relatively foolproof, and affords minimum interference with the normal activities of the aviator` A more specific object is to provide an oxygen mask incorporating a rebreathing reservoir, Without having an external bag.

Another specic object is to provide a mask that is comfortable to wear, even for relatively long periods of time.

Another specific object is to provide an oxygen mask construction that does not interfere with talking.

Still another specic object is to provide a mask construction of such nature as to inform the pilot of Vfailure of the oxygen supply.

Still other more specic objects and features fil) of the invention will become apparent from the following detailed description of a particular embodiment of the invention, which is disclosed in the drawing.

In the drawing:

Fig. 1 is a front elevation view of an oxygen mask in accordance with the invention, shown mounted on the head of a user:

Fig. 2 is a side view;

Fig. 3 is a longitudinal section through the mask, removed from the head, the section being taken substantially along the line 3-3 of Fig. l;

and

Fig. 4 is a detail sectional view, illustrating the connection between the breathing tube and the nosepiece.

Referring to Figs. 1 and 2, my mask includes as its main separate elements a nosepiece l, and a helmet 2. The helmet 2 is shaped very much the same as the conventional aviators helmet to t quite snugly over the top, back and rear side portions of the head, its front, lower edge portion extending across the forehead and thence down immediately in front of the ears, and being secured under the chin by a strap 3. It may be provided with pockets 4 for radio earphones, in accordance with established practice.

The helmet 2 differs from the conventional aviators helmet in having a double Wall over the top portion of the head to denne a rebreathing chamber 5. Thus, referring to Fig. 3, the top portion of the helmet includes an` outer wall 6 and an inner wall 1, the outer wall Sbeing of larger dimension than the innerl wall 1 Vso that the outer wall can be distended away from the inner wall to give the rebreathing chamber or reservoir 5 any desired capacity. The inner wall 1 preferably fits quite snugly against the head. Both walls 6 and 'I are made of some flexible material, such as rubber or leather, that is relatively impervious to the passage of gases therethrough, although it is not essential that they be absolutely gas-tight.l The rebreathing reservoir 5 is communicated with an oxygen supply tube 8 by a fitting 9 in the outer wall 6, and is communicated with the nosepiece I by a rebreathing tube l0, which also connects to a fitting l I in the outer wall 6 lof the helmet. The tube IIJ is-of substantially larger dimensions than the tube 8, since oxygen is supplied at a relatively constant rate through the tube 8 into the reservoir 5, whereas the user breathes in and out of the reservoir 5 through the tube I0, and it is desirable to keep the resistance Vto flow of the breathed gases as low as possible to prevent discomfort and fatigue.

The nosepiece I is made of rubber or other suitable material, and is conformed to t over the nose and mouth and seal against the face so as to define a chamber in free communication with the mouth and nose of the wearer, but free from leakage at its edge of contact with the face. The nosepieoe I is supported against the face of the wearer by a hood I5, which may be of leather and covers the chin and cheeks of the wearer to protect the face from cold, as well as to support the nosepiece I. The hood I5 has straps I6 which extend around the head of the wearer and are secured by buckles I1 to the opposite side of the hood I5 (Fig. 1). These straps I6 are slidably supported in loops I8 on the helmet 2. The rearmost loops I3 may frictionally engage the straps to prevent them from slipping longitudinally.

The breathing tube I passes through a large aperture provided therefor in the hood I5, and is connected to the wall 2) of the nosepiece l by a fitting 2| (Fig. 4). Thus the nosepiece I is in free communication with the rebreathing reservoir 5, through the rebreathing tube II) at all times.

The nosepiece I is provided with a discharge passage 22 which communicates with a rubber check valve 23 of well-known type, which permits exhaust from the nosepiece I under a relatively small pressure, but prevents any ingress of air through the opening 22 into the nosepiece.

Positioned in the front part of the nosepiece I, substantially directly in front of the mouth of the wearer, is a metal frame 29 vdefining a circular opening or window 26 behind which is a wall 21 of sound permeable material, which may be thin rubber. However, I prefer to employ a textile fabric which is somewhat permeable to gas, as well as to sound, for reasons to be described later. This wall 21 is secured in place by a ring 28 which is pressed into the frame 29 from the inside. By removing this ring 23, the wall 21 can be changed.

The exterior of the member 29 is shaped to provide an annular flange 25 which is useful in centering a microphone over the sound-permeable wall 21 when signaling by radio.

In use, with the mask positioned on the head of the wearer as shown in Figs. 1 and 2, and the tube 8 connected to an oxygen supply system, as indicated schematically at 3l) (Fig. 1), the device functions as follows: y

Initially, the outer wall 6 of the helmet may be collapsed upon the inner wall 1 so that initial inspiration causes a substantial amount of oxygen to be drawn in through the reservoir 5 through the tube 8 and at the same time some air will be drawn in through the permeable member 21. However, during the following exhalation substantially all of the air exhaled ows through the tube I0 into the rebreathing reservoir 5, expanding the outer wall 6 away from the inner wall 1. If the rate of supply of oxygen through the tube 8 is great enough it will eventually cause the reservoir 5 to be lled to capacity before the end of each exhalation, so that towards the end of each exhalation the exhaust valve 23 opens to release some of the exhaled air. Of course a portion of the air also escapes through the porous wall 21. It is important to note that the resistance to flow through the rebreathing tube I8 to and from the rebreathing reservoir 5 is so slight that practically no air flows in or out through the porous wall 21 except when the wall t is either completely collapsed or fully distended, and the constant supply of oxygen through the tube 8 tends to keep the wall 6 distended.

The oxygen supply system 30 is preferably of a well-known type, in which the volume of oxygen supplied is dependent upon the atmospheric pressure existing so that as the aviator reaches higher and higher altitudes the supply of oxygen auto matically increases. With an oxygen supply sys tem of this type connected to the tube 8, the iiow of oxygen through the tube B into the rebreathing reservoir 5 increases as the altitude increases, causing more and more of the exhaled air to be discharged through the Valve 23 as the altitude increases. At very low altitudes the supply of oxygen may be insufficient to keep the rebreathing reservoir 5 filled so that the deficiency will be made up by forced induction of air through the porous wall 21 toward the end of each inspiration.

When the supply of gas within the rebreathing reservoir 5 is insuiiicient to prevent complete collapse of the outer wall 6 against the inner wall 1, the suction produced by inhalation constricts the wall 1 about the head of the aviator so that he is conscious of the condition. This is a very desirable feature of the invention, since it provides an automatic signal to the aviator in case of failure of the oxygen supply through the tube 8, due to exhaustion of the source of supply, or a pinching ofi of the tube 8 by any cause.

When it is not desired to supply oxygen, the hood I5, carrying the nosepiece I, can be swung out of the way by undoing the buckles I1, swinging the hood i5 across the back of the helmet and again securing the ends of the strap I6 to the buckles I1.

It will be observed that by incorporating the rebreathing reservoir in the helmet structure, the necessity of an external bag for rebreathing purposes is completely eliminated. This not only greatly improves the appearance of the device, but is advantageous because of the elimination g of loose hanging external parts which may get in the Way, or have their proper operation interfered with.

Although for the purpose of explaining the invention a particular embodiment thereof has been described in detail, it is to be understood that various departures from the exact construction shown can be made without departing from the invention, which is to be limited only to the extent set forth in the appended claims.

I claim:

1. A device of the type described comprising a head-tting cap consisting of double walls dening therebetween an expansible and contractable rebreathing reservoir, means for effecting a breathing connection to said reservoir, and means for supplying a breathing gas to said reservoir.

2. A device as described in claim 1, in which said double walls include an inner wall closely tting the head of the wearer, and an outer wall coextensive with said inner wall and of larger dimensions whereby it is distensible away from said inner wall.

3. A device as described in claim l, in which said means for supplying a breathing gas to said reservoir includes a gas connection on said cap at the rear portion thereof, and substantially at the rearmost portion of said reservoir.

4. A device for supplying oxygen to an aviator,

comprising means dening a breathing chamber in front of the mouth of a user, means for supplying breathing gas to and from said chamber, and a sound permeable wall positioned in front of the mouth of the wearer and constituting a part of said chamber-defining means, said wall also being somewhat permeable to air to permit restricted ow of air therethrough for supple inenting said breathing gas.

5. A device for supplying oxygen to an aviator, comprising in combination means delining a breathing chamber in front of the mouth of a user, means defining an expansible rebreathing chamber, an oxygen supply system adapted to supply a larger volume of oxygen at low atmospheric pressures than at high atmospheric pressures, and means connecting it to said rebreathing reservoir, in which said means defining said breathing chamber comprises a wall member permeable to restricted flow of gas therethrough in response to pressure, whereby at high atmospheric pressures more air is inhaled through said wall member than at low atmospheric pressures.

6. Apparatus for supplying a breathing gas to a person, comprising a member adapted to lie against and be supported by the head of said person and defining an expansible and contractable rebreathing reservoir, means for effecting a breathing connection between a breathing orice of said person and said reservoir, and

means Vfor supplying a breathing gas to said reservoir; in which said member comprises an inner reservoir wall and an outer reservoir Wall substantially coextensive with and overlying said inner wall and connected thereto at its margins to denne therewith said reservoir, said inner wall being dimensioned to conform to the shape of said head and lie snugly against said head over substantially the entire area of said inner wall, irrespective of the extent of expansion of said reservoir.

'7. Apparatus for supplying a breathing gas to a person, comprising a member adapted to lie against and be supported by the head of said person and defining an expansible and retractable rebreathing reservoir, means for effecting a breathing connection between a breathing orice of said person and said reservoir, and means for supplying a breathing gas to said reservoir, said member comprising an inner reservoir wall and an outer reservoir wall substantially coextensive with and overlying said inner wall, and connected thereto at its margins to dene therewith said reservoir, said member including means constraining the marginal portions of said inner wall toward said head, whereby said inner wall remains concave on the side next to the head irrespective of the extent of ination of said reservoir.

SILAS A. MOREHOUSE. 

